Add mass action cookbook (#45)

* Add mass action cookbook

* Update docs/backend/cookbook/new_mass_action.md

Co-authored-by: wfajczyk <37833669+wfajczyk@users.noreply.github.com>

Author: rprzedzik

docs/backend/cookbook.md

@@ -10,5 +10,6 @@
 * [New Grid Column Type](backend/cookbook/new_grid_column_type.md)
 * [New Condition](backend/cookbook/new_condition.md)
 * [New Channel](backend/cookbook/new_channel.md)
+* [New Mass Action](backend/cookbook/new_mass_action.md)
 
 

docs/backend/cookbook/new_mass_action.md

@@ -0,0 +1,34 @@
+# How to create new mass action
+
+## Mass action processor class
+
+Any custom mass action process must implement ```BatchActionProcessorInterface``` 
+
+```php
+namespace YourNameSpace\Infrastructure\Processor;
+
+use Ergonode\BatchAction\Domain\Entity\BatchActionId;
+use Ergonode\BatchAction\Domain\ValueObject\BatchActionMessage;
+use Ergonode\BatchAction\Domain\ValueObject\BatchActionType;
+use Ergonode\BatchAction\Infrastructure\Provider\BatchActionProcessorInterface;
+use Ergonode\SharedKernel\Domain\AggregateId;
+
+class YourBatchActionProcessor implements BatchActionProcessorInterface
+{
+    public function supports(BatchActionType $type): bool
+    {
+        return $type->getValue() === 'you type';
+    }
+
+    /**
+     * @return BatchActionMessage[]
+     */    
+    public function process(BatchActionId $id, AggregateId $resourceId): array
+    {
+        // here implement your action for given AggregateId 
+    }
+}
+```
+
+If, for some reason, a mass action can't be processed for a given object, you can return information about it as array of ```BatchActionMessage``` objects
+In whole batch action this object is marked processed as unsuccessful.